Northern Ireland could be used to smuggle illegal drugs and weapons from the EU into Britain after Brexit, police have warned.
The Irish land border will remain porous and organised crime experts believe strengthened UK frontiers could prompt criminals to seek alternative routes via the Republic.
The UK prime minister has pledged to ensure unfettered access for Northern Irish goods to the rest of the UK following Brexit.
Police Service of Northern Ireland (PSNI) chief constable Simon Byrne warned against leaving a “soft underbelly” for gangsters to exploit.
He said: “We assess that Northern Ireland could act as the conduit for a range of goods from the EU into Great Britain.
“This will not only facilitate legitimate business, but also potentially a range of illegitimate businesses.”
Crossing points
The Irish border covers 310 miles from Lough Foyle in the west to Carlingford Lough, with more than 300 crossings points. Police forces on both sides work closely together to tackle criminality.
PSNI chief Mr Byrne said "further clarification" regarding the "unfettered" access of goods promised by Boris Johnson would be welcome, as he appeared before the Northern Ireland Affairs Committee of MPs on Wednesday.
“It is our concern that this could establish new and improved routes for importing of contraband into Northern Ireland and Great Britain, including drugs and weapons," he said.
Mr Byrne said law enforcement agencies will need increased resources to target criminal groups, gather intelligence on organised crime groups and improve search and detection capability at points of entry.
There is an associated risk linked to the trafficking of vulnerable persons
“There is an associated risk linked to the trafficking of vulnerable persons," the PSNI added.
“Enhanced information recording and data sharing relating to sea travel would greatly assist to deter and investigate the criminal exploitation of these routes.”
UK National Crime Agency operations director Steve Rodhouse warned that some criminals will see strengthened British borders as a risk and may take an “alternative route” to bring commodities into the UK via the Republic of Ireland.
He added: “It is helpful for UK security for the Republic’s borders to be as effectively policed as possible.”
Police in Northern Ireland believe there are “significant opportunities” to develop new approaches such as a bespoke centre of excellence relating to crime co-operation and co-ordination with Irish counterparts.
Police in the North are armed while their Irish counterparts in An Garda Síochána are not, prohibiting hot pursuit of offenders south and leaving officers relying on communicating with each other via telephone to apprehend suspects.
Mr Byrne said: “What we are looking to do is see if we can develop that hot pursuit policy both ways further post-January to see if there is any way we can overcome these problems that we are armed and, largely, the Garda are not.”
